Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

How the brakes work and how they failed


When a Northern Line train passes a red light, a trip cock is triggered and activates three switches.

The rst two operate emergency brakes while the last switch prevents the train from driving at full speed for three minutes from the time the train comes to a stop.

During a routine check on 6 September, the third switch failed to activate when the train approached a stop signal at low speed.

Six of these switches - located under seats behind the driving cars on every Northern and Jubilee Line train - have been replaced in the last two weeks.

The new switches now operate at 6.5 bar pressure, 2.7 bar more than before to ensure they trigger the goslow safety mechanism.

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.